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HENRY oQLofrHnoP., or MILFORD, MASSACHUSETTS.

LettersV Patent No. 75,034,"datedllfarch 3, 1868,

IMPROVEMENT Iil STEAM-ENGINE GvUT-OFFS.

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Be it known that I, HENRY O. LOTHROP, of Milford, in thc county ofWorcester, and Commonwealth of Massachusetts, have invented certain newand useful Improvements in Steam-Engines, or in the inode of operatingthe cut-olf of the-same; and do hereby declare the following to be afull, clear, and exact description thereof, due reference being had tothe accompanying drawings, making part of this specification, and inwhich- Figure 1 is a vertical and longitudinal section, and

Figure 2 a vertical and transverse section ofthe cylinder, steam-chest,and valvo of a steam-engine with my invention or improvement appliedthereto.

Figure 3 is a plan-of the same, with the top plate of the steam-chestremoved.

Figure 4 is a plane development of one of the actuating-cams,;to behereinafter described.-

The object of this invention is to enable the regulator of the engine toso operate the cut-of as to increase or diminish the supply of steam 'tothel cylinder according to the wants of they engine, the invention beingintended principally for application .to an engine constructed inaccordance with the plan shown in an application for a. patent newpending before the Patent Oce, and also to that class of steam-enginesin which two sets ofcylinders of different capacitiesare employed, andin which the steam from the smaller is exhausted in to and employed i nthe larger, although the invention possesses merits which render itsapplication valuable Y to-an engine of ordinary construction. c

The invention consists in the combination, with the ordinary valve of asteam-engine, of two drop-plates or auxiliaryvalves,l one at each. endof the primaryvalve, and operating inconnection with ports made throughsuch ends of the primary valve, the auxiliary valves being operated bycams applied to a revolving shaft suitably within the steam-chest, andoperated with one unchanging motion by the driving-shafts `of theengine,'a suitable lateral motion being imparted to the said cams by theagency of a sliding rod which extends Ainto the cam-s-hafand is actuatedby the regulator, substantially as hereinafter explained.

AIn the accompanying drawings, which represent a steam-engine cylinderconstructed in accordance with my application befre referred to, Adenotes ythe cylinder of theengine, B C being the steam-ports leadingfrom the steam-.chest to such cylinder, and B the exhaust-port. Theprimary valve is shown at D, its eccentricred being shown at E. .Achamber, F or G, is formed in the lower part of the 4valve D, and neareach end thereof, ports E I being cut through the valve, and openingcommunication from' the chambers F and G t0 the interior of thesteam-chest, which is shown at J, The object of making this chamber andport in each end of the valve is to enable the device to work moredirectly and freely, and more particularly to facilitate the mechanicalconstruction of it. The drop auxiliary valves K L are disposed withinthe steam-chest J, and over the ports H I, and are hinged (as shown at aa() attheir inner edges to the opposite side walls of the steamchest,and between the extreme movements of'such ports, in such manner as toform,'with the upper surface of the primary valve and surrounding portsH I, a tight `ioint or seat when Vlowered to their lowest extent, and tobe capable of heing raised o' such seats at a proper time and allowsteam from thesteam-chest to pass through said ports and into thecylinder. The auxiliary valves K L are provided at' their inner edgeswithvtrippinglevers or ngers, b, such fingers bearing againstthe-peri'pheries of twocam's, c d, which slide upon a revolving tubularshaft or sleeve, c, which is suitably supported in bearings,fg, made inthe walls of the'steam-chst.

One end of such shaft, which extends through the side of thesteam-chest, and is provided at its outer extremity ywith a crank, 71.2,is connected with the driving-shaft of the engine by bevel-.gears insuch manner that the revelutions of such shaft shall cause acorresponding number of revolutions of the shaft c. The bearing-surfacesof the cams c d are semicircular in vertical section, and are placedopposite each other upon the shaft e, inorder that. when one of suchcams has depressed its valve-lever, the other cam shall be out ofcontact with its valve;

finger or tripping-lever of such valve, one tripping-lever, viz, thatmarked b in the drawings, being extended underneath andbearing againsttho inner side of its cam, in order to allow of a rotary motion of thecams in one'direction. A rod, z', slides freely within the tubular shafte, and at its outer endis connected with the govcrnorz of the engine insuch manner that-the rising and falling or fluctuations of such governorsh'all cause corresponding lateral movements of the rod z'. The cams cand d are connected to this rodin such manner as to be moved laterallyby it, and slide upon the tubular shaft e during the fluctuations of,the governo1,'whileat the same time they, as well as the rod, arerevolved by and with such tubular shaft. To accomplish this, setscrews,7c and Z, are screwed through each hub of the cams, and extend intogrooves, m n, cut inthe periphery of the rod z', two slots, a j), beingcat in the tubular shaft for the reception of such screws, and to allowof the lateral motion of thecams upon it. The shape of the cams c d asdeveloped are trapezoidal, as shownin iig.y 4 of the drawings. Y

-As the regulator-balls lower, the rod z' is moved outwardly, and bymoving the cams c n. in the same direc- Lion expose a larger amount oftheir periphery to actuate the lingers a li, and by so doing` hold up orkeep open the valves for a greater length of time, and allow more steamto enter the cylinder. A reverse movement of the cams will take placeupon increased speed of the regulator, and diminish the quantity ofsteam admitted to the cylinder, it being understood that the valves K Ldrop upon the main valve when either finger passes from contact with theperiphery of its cam.

We will suppose the main vvalve to be in the position at the extremeleft ofits movement, and with the port I beyond and uncovered by theauxiliary valve L, such auxiliary valve being raised bythe action ofthecam d upon its :linger 6, and' the steam passing from Ythe steam-chestintoand supplying the chamber G ready for Ventrance to the cylinder. Themain valve, by the action of' its eccentric, now moves in the`direetionof the arrow thereon, until it arrives at'the position (beitiive-eiglithss'troke, more or less,) in 'which the requirements Iofthe'engine causethe governor to bring the cam d into such a positionas to close theauxiliriry valve L, or

let it drop down upon thcupper surface of the mitin -valve and close theport I, thus cutting oil' steam from the cylinder at this end, andallowing -tbe valve D to complete the remainder of its movement in thisdireetiouwith.- 'out the admission oi' more steam, it being understoodthat the area oi the auxiliary valve L is suiciently large to cover theport I during such movement. As the valve reaches'its extreme movementin this direction at the right of the steam-chest, and starts to return,'the auxiliary valve K is opened by the action ofthe cam c upon lthefinger a, and the steam allowed to enter the chamber F through the portH, ready for admission to the lcylinder. As the action ofthe valve whenmoving inthis direction is the sanie relatively as in the movement lastdescribed, its operation will be readily understood. l l

Should the engine be increasing in speed at too rapid a rate, thegovernor will move the rod z' inwards, and by bringing ashorter or lessbearing-surface of the cams c d to act upon the fingers a 6, cause thevalves alternately to drop down upon and elosethe ports II and Iquicker,and consequently cut off the steam at a less length of stroke of thepiston.` Should the speed of the engine be'deereasing atptoo great anextent, the lowering of the balls of the governor will cause the rod z'to move in an opposite direction, and bring a larger portion oftheperiphery of the cams e i to bear upon the fingers a b, and by keepingthe ports HI open for a greater length of time, allowing a larger amountof steam to enter the cylinder.

It will be seen that while one cam is in contact lwith and operating onefinger, the blank space of its fellow cum is passing by the other ngerwithout actuating I claim the improved cut-oif.regulating-mechanismherein described, consisting of the auxiliary valvesK L, operated by the cams c and d', applied to the shaft c and slidesz', the whole operating in combination with the main valve-D andcylinder-ports B and C, to produce the results before set forth andexplained.

HENRY O. LOTHRO-P.

Witnesses:

FREDERICK CURTIS, E. C. GRIFFITH.

